Corresponding Author: Elke Hattingen, MD, Goethe-University Hospital Frankfurt, Schleusenweg 2-16, 60528, Frankfurt, Germany.
Neuro Oncol. 2013 Oct;15(10):1395-404. doi: 10.1093/neuonc/not105. Epub 2013 Aug 7.
Anti-angiogenic treatment in recurrent glioblastoma patients suppresses contrast enhancement and reduces vasogenic edema while non-enhancing tumor progression is common. Thus, the importance of T2-weighted imaging is increasing. We therefore quantified T2 relaxation times, which are the basis for the image contrast on T2-weighted images.
Conventional and quantitative MRI procedures were performed on 18 patients with recurrent glioblastoma before treatment with bevacizumab and every 8 weeks thereafter until further tumor progression. We segmented the tumor on conventional MRI into 3 subvolumes: enhancing tumor, non-enhancing tumor, and edema. Using coregistered quantitative maps, we followed changes in T2 relaxation time in each subvolume. Moreover, we generated differential T2 maps by a voxelwise subtraction using the first T2 map under bevacizumab as reference.
Visually segmented areas of tumor and edema did not differ in T2 relaxation times. Non-enhancing tumor volume did not decrease after commencement of bevacizumab treatment but strikingly increased at progression. Differential T2 maps clearly showed non-enhancing tumor progression in previously normal brain. T2 relaxation times decreased under bevacizumab without re-increasing at tumor progression. A decrease of <26 ms in the enhancing tumor following exposure to bevacizumab was associated with longer overall survival.
Combining quantitative MRI and tumor segmentation improves monitoring of glioblastoma patients under bevacizumab. The degree of change in T2 relaxation time under bevacizumab may be an early response parameter predictive of overall survival. The sustained decrease in T2 relaxation times toward values of healthy tissue masks progressive tumor on conventional T2-weighted images. Therefore, quantitative T2 relaxation times may detect non-enhancing progression better than conventional T2-weighted imaging.
抗血管生成治疗在复发性胶质母细胞瘤患者中抑制对比增强并减少血管源性水肿，而非增强性肿瘤进展较为常见。因此，T2 加权成像的重要性正在增加。我们因此量化了 T2 弛豫时间，这是 T2 加权图像对比的基础。
在贝伐单抗治疗前和之后每 8 周，对 18 例复发性胶质母细胞瘤患者进行常规和定量 MRI 检查。我们在常规 MRI 上将肿瘤分割为 3 个亚体积：增强肿瘤、非增强肿瘤和水肿。使用配准的定量图，我们跟踪了每个亚体积的 T2 弛豫时间的变化。此外，我们通过使用贝伐单抗下的第一个 T2 图作为参考进行体素减法生成了差分 T2 图。
肿瘤和水肿的视觉分割区域的 T2 弛豫时间没有差异。贝伐单抗治疗开始后，非增强肿瘤体积没有减少，而是在进展时显著增加。差分 T2 图清楚地显示了在先前正常的大脑中的非增强肿瘤进展。T2 弛豫时间在贝伐单抗治疗下减少，但在肿瘤进展时没有再次增加。贝伐单抗治疗后增强肿瘤的 T2 弛豫时间减少<26ms 与总生存期延长相关。
结合定量 MRI 和肿瘤分割可改善贝伐单抗治疗的胶质母细胞瘤患者的监测。贝伐单抗治疗下 T2 弛豫时间的变化程度可能是预测总生存期的早期反应参数。T2 弛豫时间朝着健康组织的值持续下降掩盖了常规 T2 加权图像上的进行性肿瘤。因此，定量 T2 弛豫时间可能比常规 T2 加权成像更好地检测非增强性进展。
